Protesters in St. Louis Friday night blocked highways, damaged public and private property, broke windows, threw rocks at the mayor's house and threw bricks at police officers -- who responded by dispersing tear gas -- after a white former police officer earlier in the day was acquitted in the 2011 fatal shooting of a black man.

Thirteen people were arrested, the St. Louis Metropolitan Police Department said. Eight officers were injured, two of whom was transported to a hospital with injuries sustained after being hit by a brick. Some officers were wearing protective gear due to items being thrown at them,

St. Louis Circuit Judge Timothy Wilson found 36-year-old Jason Stockley not guilty of first-degree murder and armed criminal action. On Dec. 20, 2011, the then-police officer shot 24-year-old Lamar Smith five times after a high-speed chase and crash.

Police guard on-ramps to Interstate 64 as protesters gather, Sept. 15, 2017.Police line up as protesters gather, Friday, Sept. 15, 2017, in St. Louis, after a judge found a white former St. Louis police officer, Jason Stockley, not guilty of first-degree murder in the death of a black man, Anthony Lamar Smith, who was fatall

Hundreds of people we re part of the massive protest, ABC St. Louis affiliate KDNL reported.

At 10:08 p.m. local time, police declared the gathering an "unlawful assembly," tweeting, "those refusing to leave are subject to arrest."

Less than 20 minutes after tweeting that the protest was an unlawful assembly, police announced tear gas had been dispersed, tweeting, "Tear gas was deployed because agitators became violent towards officers and destroyed property at Kingshighway & Waterman #stlverdict."

Police took to Twitter documenting the violent aspect of the protest, including the blocking by protesters of highways and other thoroughfares and other acts of civil disobedience.

The violence continued past 11 p.m., with police tweeting at 10:29 p.m., "Destruction of public and private property continues in the #CWE neighborhood. We are doing everything we can to keep you safe #stlverdict." Then at 11:30 p.m. police tweeted, "Agitators are being warned that this is no longer a lawful assembly. If they do not disperse, they will be subject to arrest. #stlverdict."

Damone Smith, a 52-year-old electrician who was among the motorists re-routed away from the area, told the St. Louis Post-Dispatch that he believed the verdict to be âdisgusting.â

âIâm proud of these people protesting,â Smith, who is black, to ld the Post-Dispatch. âIf you look like me, then you feel like there is no other way to express yourself in this kind of verdict. Time and time again, African-American men are killed by police, and nobody is held accountable.â

A protester runs from the police, Friday, Sept. 15, 2017, in St. Louis, as protesters rally around the home of St. Louis Mayor Lyda Krewson, after a judge found a white former St. Louis police officer, Jason Stockley, not guilty of first-degree murdeProtesters march in St. Louis, after a judge found a white former St. Louis police officer, Jason Stockley, not guilty of first-degree murder in the death of a black man, Anthony Lamar Smith, Sept. 15, 2017.

Officials also tweeted a video of protesters stomping on the hood of a police car.

Some demonstrators were seen openly carrying rifles on the streets, which is legal in Missouri, according to The Associated Press, but there have been no reports of weapons being fired.

Protesters march in St. Louis, after a judge found a white former police officer, Jason Stockley, not guilty of first-degree murder in the death of a black man, Anthony Lamar Smith, Sept. 15, 2017.

Earlier in the evening, police said the protests have been "for the most part" nonviolent, adding "there have been some tense moments where agitators became destructive."

Protesters march down, Friday, Sept. 15, 2017, in downtown St. Louis, after a judge found a white former St. Louis police of ficer, Jason Stockley, not guilty of first-degree murder in the death of a black man, Anthony Lamar Smith, who was fatally sho

Several companies -- including Wells Fargo, Stifel and Nestle Purina Petcare -- sent thousands of employees home as protests grew Friday morning, the Post-Dispatch reported.

Stockley told the Post-Dispatch on Friday that he âcan feel forâ and âunderstandâ what Smithâs family is going through. âI know everyone wants someone to blame, but Iâm just not the guy,â Stockley told the local newspaper.

Stockley's acquittal also elicited outrage from several local officials, condemning the anxiously awaited bench verdict.

"This not-guilty verdict of a police officer who violently killed a citizen is another slap in the face to the black community in St. Louis,â Missouri state Rep. Michael Butler said in a statement. âAnd a shot in the heart to the family of the victim,â he said of Smith.

âThis system and all the politicians calling for peace are ignoring the pain this verdict causes our communities,â Butler added. âWe will be nonviolent but we will not settle on peace. No justice. No peace.â

Protesters march after the not guilty verdict in the murder trial of Jason Stockley, a former St. Louis police officer, charged with the 2011 shooting of Anthony Lamar Smith, who was black, in St. Louis, Missouri, Sept. 15, 2017.

St. Louis Mayor Lyda Krewson offered a more measured response, though equally emotional.

"My thoughts and prayers are with the family and friends of Anthony Lamar Smith, our police, judge, prosecutor, our citizens who find no comfort or justice, and everyone involved in this difficult case," she said in a statement.

"I am appalled at what happened to Anthony Lamar Smith. I am sobered by this outcome. Frustration, anger, hurt, pain, hope and love all intermingle."

Stockley and his partner at the time, Brian Bianchi, were trying to apprehend Smith for a suspected drug deal at a Church's Chicken restaurant, according to court documents.

Stockley was facing up to life in prison without parole had he been convicted of both charges.

Crowds of people gathered today near the courthouse in downtown St. Louis to protest the ruling. Police blocked streets nearby so demonstrators could march.

Missouri Gov. Eric Greitens, anticipating protests in response to the controversial ruling, released a statement saying he understood the verdict is painful for many St. Louisans.

"The boxed us in and started peppy spraying us," said Mackenzie Marks of St. Louis, who her eyes washed out after being pepper spray protesting the not guilty verdict in the killing of Anthony Lamar Smith, Sept. 15, 2017.

"We know this verdict causes pain for many people," Greitens said. "I'm committed to protecting everyone's constitutional right to protest peacefully, while also protecting people's lives, homes and communities. For anyone who protests, please do so peacefully."

Stockley's defense attorneys argued that the then-officer acted "reasonably&q uot; in self-defense in killing a drug suspect he believed was reaching for a hidden gun.

Prosecutors alleged that Stockley planted a .38-caliber revolver in Smith's Buick after he shot him.

Protesters yell at law enforcement officers on the steps of the Old Courthouse following a verdict in the trial of former St. Louis police officer Jason Stockley in St. Louis on, Sept. 15, 2017.

In his verdict, Wilson wrote that the court "is simply not firmly convinced of [Stockley's] guilt."

And because prosecutors "failed to prove beyond a reasonable doubt that [Stockley's] use of deadly force was n ot justified in self-defense," Wilson wrote that he could not address lesser charges of homicide, including involuntary manslaughter.